What might indicate a need for varied air changes in a space?

The need for varied air changes in a space is primarily indicated by changes in occupancy and activity levels. Different activities and varying numbers of occupants produce different amounts of pollutants and carbon dioxide, necessitating adjustments in the air exchange rate to maintain acceptable indoor air quality and comfort. For instance, an increase in occupancy, such as hosting a large gathering, requires more frequent air changes to effectively ventilate the space and remove excess CO2 and other contaminants. Similarly, activities that generate more pollutants (like cooking or exercising) also necessitate increased ventilation. Monitoring these factors ensures that the indoor environment remains healthy and comfortable for occupants.

The other options, while they might influence comfort, do not directly relate to the operational changes needed for ventilation rates based on occupancy and activity. Standard occupancy levels provide a baseline, while ambient noise levels and outdoor environmental conditions are not the primary drivers for changing air change rates.